// 比如这个a中，就有四层。如何算出这四层const a = {  b: 1,  c() {},  d: {    e: 2,    f: {      g: 3,      h: {        i: 4,      },    },    j: {      k: 5,    },  },};

js

function testLevel(param) {  const isObject = Object.prototype.toString.call(param) === '[object Object]';  if (!isObject) return 0;  const level = 1;  let childrenLevel = 0;  Object.entries(param)    .map(([key, value]) => {      const valueLevel = testLevel(value, level);      if (valueLevel > childrenLevel) childrenLevel = valueLevel;    });  return level + childrenLevel;}